Posterior Circulation Strokes

Clarify what the patient means by dizziness regarding timing and triggers of the onset of symptoms. Distinguish dizziness from syncope or other mimicking conditions, as these will require a different work-up.

Suspect a central etiology in patients with acute vestibular syndrome. Evaluate with the HINTS exam.

Use the HINTS test in patients presenting with Acute Vestibular Syndrome, as this is more sensitive than both CT and MRI for posterior circulation strokes.

Nystagmus is assessed during lateral gaze at 45-60 degrees, not at end-gaze. An abnormal response in a patient with AVS is vertical or torsional nystagmus.

The HINTS exam should only be used in patients presenting with Acute Vestibular Syndrome, not patients with Triggered or Spontaneous Episodic Vertigo Syndrome.

Pitfalls

Symptoms that worsen with movement do not confirm a peripheral process. Symptoms with movement may also exacerbate symptoms from a central process.

A normal head CT is not sufficient in excluding ischemic stroke.

MRI should not be relied upon in the initial 24-48 hours after symptom onset to rule out a posterior circulation stroke, as it may miss up to 10-20% of posterior circulation strokes.

Younger age does not exclude central causes of Acute Vestibular Syndrome. A stroke should still be suspected in patients younger than 50 if the physical exam is concerning for a central process.

Many of the classic distinguishing features of peripheral lesions are also found in central lesions."